1. Field of the Invention
This invention relates to a multiple magnetoresistance element and more particularly to a multiple magnetoresistance element having selectivity of wave length for periodic magnetic signals.
2. Description of the Prior Art
Hitherto, a multi-gap magnetic head is used as a detecting element having selectivity of wave length for periodic magnetic signals such as a magnetic scale. However, the multi-gap magnetic head is apt to be affected by change of temperature and external magnetic fields. Coil windings are required. Moreover, saturable cores are required for the multi-gap magnetic head, since it is of the magnetic flux responding type. Therefore, the apparatus using the multi-gap magnetic head has the disadvantage that it is complicated in construction and that it is expensive.
The selectivity of wave length means the function to detect selectively signals with specific frequencies from a composite signal with different frequency components. When the multi-gap magnetic heads detect the repeated magnetic signals which are recorded on the magnetic scale, the selectivity of wave length means the function to detect selectively signals with wave lengths twice, four times, six times . . . as long as the distance between the adjacent gaps of the multi-gap magnetic head, from the repeated magnetic signals.